The present invention relates to medical treatments which require delivery of a chemical or biological material to a defined region in a physiologic passage, which may be a blood vessel, the urinary canal, or some other passage.
For example, it may be desired to remove blockages and deposits associated with medical conditions of a wide degree of severity, ranging from those which produce physical discomfort to those which are life threatening. In addition, there are known chemical and biological materials which are effective to prevent restenosis or cell division, or which may be used, for various medical purposes, to coat the wall of a physiologic passage.
Accordingly, a large number of techniques offering the possibility of performing such procedures have been investigated. Among these techniques are those involving the use of appropriate dissolution chemicals. However, while such chemicals and biological materials are known, these materials also produce side effects in the human body which have prevented their safe use.
The preceding applications, cited above, disclose the details of a procedure which allows a dissolution chemical to be partially localized and concentrated at the site of a deposit and allows the relative proportions of dissolution chemical and blood to be adjusted. The concept of this approach is to create a controlled minienvironment.
It has now been found that the apparatus previously employed for carrying out this method did not allow complete control of the conditions essential to optimum implementation of the method i.e., the calibration and control of the "minienvironment" so designated as the area under treatment in a manner which enables optimal effects to be obtained within this environment while minimizing the toxic effects of the chemical or biological material to other sites in the body.